Steel in Keel Fuel Tank Overhaul or Plastic Tanks

[Rustic Charm]

Originally Posted by Terra Nova

Because of the tank's poor accessibility, I think cutting into the side is the right approach. But I would avoid adding any internal coatings. Adding a new day tank is a very good idea. This one should have a convenient sump and drain at the bottom, and sufficient clean-outs at the top (preferably). Fuel from the main tank can be filtered at transfer.

I was also advised today not to seal it with anything. I was advised there is no product available that would stick sufficiently to the diesel without a very significant sand blasting. Something which given my tank construction is not possible. So I was advised to leave it raw. A header tank and fuel polishing system is what was suggested today.

I'm leading strongly towards cleaning this tank, which means cutting a large enough 'door' into the side of it, to scrape, steam and wire wheel out the inside in all the areas.

[Rustic Charm]

This is what the bottom of my tank looked like in December prior to me filling it, AFTER I had vacuumed it out, washed in petrol and vacuumed it out again. This looks like a muddy sludge but it's gone solid. I had thought it was some kind of sealer someone had poured into it, but I was told today it's diesel sludge solidified.

[unclemack]

Do you think the sludge has absorbed some petrol and become mobile again?


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[Rustic Charm]

Originally Posted by unclemack

Do you think the sludge has absorbed some petrol and become mobile again?


Sent from my GT-I9505 using Cruisers Sailing Forum mobile app

Diesel tank it is.

[hoppy]

Couldn't you just skip the keel tank and fit alu/plastic tank's in the bilge that will be easy to clean in the future?

[Rustic Charm]

Originally Posted by hoppy

Couldn't you just skip the keel tank and fit alu/plastic tank's in the bilge that will be easy to clean in the future?

Well, yes, that is the option I was asking in the thread. Much more expense, and I'm left to work out what to do with the empty keel. But, yes it is an option.

[hoppy]

Originally Posted by Rustic Charm

Well, yes, that is the option I was asking in the thread. Much more expense, and I'm left to work out what to do with the empty keel. But, yes it is an option.

Haha I just noticed the "or Plastic Tanks"

Maybe as well as looking at the upfront cost, you should look at the long term maintenance in terms of cost and mental anguish. Given your recent experience I'd be wanting an easy to inspect and clean tank. But as the tank is only a small part of your problem, I can understand why you would want to keep the expenditure low... Then again, maybe if you keep it, you might cause the same problem with the new motor.

[unclemack]

Originally Posted by Rustic Charm

Diesel tank it is.

Maybe I've missed something.

Didn't you just post that you'd previously washed the tank in petrol?

If that's diesel sludge then the petrol will have softened it ready for the sloshing diesel to re-mobilise it in the rough seas you met.

It probably won't have softened the twenty-year-old deposit at the bottom but the upper layer would be plenty.

I have 800 litres of diesel in my steel keel and no idea yet how bad the access might be. First I'll need to remove the 350 litre stainless water tank the designer so brilliantly decided to park right on top of it.

Fitted a day tank & pre/post filters now though which keeps the engine safe - for now.

Provisional plan is to remove the water tank and use an air powered needle-scaler and scrapers on articulated poles - among other things - when it gets to the top of the list of jobs and there's only 20 litres or so in the tank.

Toilet roll filter and transfer pump for continuous "polishing" while I do it over however many days it takes. Frequent inspections with the bore-scope camera.
Not going to do it more than once.

[billy62]

To repair old motorbike fuel tanks i would fill them with molasses overnight then flush them to remove the rust. Metho to help remove the last of the water used to flush the molasses. Then line them with military grade fuel tank epoxy. It was a long term and easy cure. I suppose any product that dissolves the problem ( sludge ) is the first thing in.

[Jim Cate]

Originally Posted by billy62

To repair old motorbike fuel tanks i would fill them with molasses overnight then flush them to remove the rust. Metho to help remove the last of the water used to flush the molasses. Then line them with military grade fuel tank epoxy. It was a long term and easy cure. I suppose any product that dissolves the problem ( sludge ) is the first thing in.

I wonder if that is where the folks at the Bundaberg Rum distillery get their feedstock... explains the taste of that product!

Seriously, how did you come up with the idea of molasses? Not on the Betty Crocker list of cleaning agents!

Jim

[Rustic Charm]

Originally Posted by billy62

To repair old motorbike fuel tanks i would fill them with molasses overnight then flush them to remove the rust. Metho to help remove the last of the water used to flush the molasses. Then line them with military grade fuel tank epoxy. It was a long term and easy cure. I suppose any product that dissolves the problem ( sludge ) is the first thing in.

Molasses? You fill your tank with sugar? How does sugar do anything?

[Rustic Charm]

Originally Posted by unclemack

Maybe I've missed something.

Didn't you just post that you'd previously washed the tank in petrol?

If that's diesel sludge then the petrol will have softened it ready for the sloshing diesel to re-mobilise it in the rough seas you met.

It probably won't have softened the twenty-year-old deposit at the bottom but the upper layer would be plenty.

I have 800 litres of diesel in my steel keel and no idea yet how bad the access might be. First I'll need to remove the 350 litre stainless water tank the designer so brilliantly decided to park right on top of it.

Fitted a day tank & pre/post filters now though which keeps the engine safe - for now.

Provisional plan is to remove the water tank and use an air powered needle-scaler and scrapers on articulated poles - among other things - when it gets to the top of the list of jobs and there's only 20 litres or so in the tank.

Toilet roll filter and transfer pump for continuous "polishing" while I do it over however many days it takes. Frequent inspections with the bore-scope camera.
Not going to do it more than once.

Yes, I finished off washing it with petrol and then sucked out what was left with a Vac. The brown solid on the bottom, I thought was some sort of sealer someone had poured into the bottom. I hadn't realised it was diesel bug/gunk. I didn't refill the tank with fresh diesel for a few weeks later as I was having the boat sandblasted and painted. Also, a 1/4 hole I'd accidentally drilled into the bottom of the tank had to be welded up. It's possible, that some of this gunk was softened. But I doubt much of it, or I would have seen it in the filter bowl.

If I had known that petrol would soften it, and that it was gunk, I would have put ten ltrs of petrol in it and left it in it.

[Uncle Bob]

Originally Posted by Rustic Charm

Yes, I finished off washing it with petrol and then sucked out what was left with a Vac. The brown solid on the bottom, I thought was some sort of sealer someone had poured into the bottom. I hadn't realised it was diesel bug/gunk. I didn't refill the tank with fresh diesel for a few weeks later as I was having the boat sandblasted and painted. Also, a 1/4 hole I'd accidentally drilled into the bottom of the tank had to be welded up. It's possible, that some of this gunk was softened. But I doubt much of it, or I would have seen it in the filter bowl.

If I had known that petrol would soften it, and that it was gunk, I would have put ten ltrs of petrol in it and left it in it.

Ted, I had a problem with bug in my tanks, supposedly 500 liters each, caused much stalling etc until I treated the fuel and ran it through a simple high volume fuel transfer pump (same as used for refueling earth moving equip etc ) fitted with a large water separator / filter assy fitted to the suction side of the pump. I use a long wand made from electrical conduit that reaches the bottom of the tank.
Had to cycle it through several times, and several filters, until no more gunk in the filter bowl.
Now I use it approximately every 6-8 months as a preventative measure and all is good to date ( touch wood ).
The initial process removed a surprising amount of crap.
Could be worthwhile in your case and a lot easier and cheaper than cutting the keel open.

[unclemack]

Not having seen, felt, poked, smelled or licked that brown stuff I've no way of knowing whether it's diesel sludge or something else.

Lead ballast when not cast in place is sometimes added as shot. Heard of tar/pitch covering the lead but I expect other sealants have been used.
It is possible for petrol to degrade substances that are unaffected by diesel.

Do you have any ideas about what else could have blocked your filters so thoroughly if you don't think it was the brown stuff? Given that you said it was fresh diesel?

[Rustic Charm]

Originally Posted by unclemack

Not having seen, felt, poked, smelled or licked that brown stuff I've no way of knowing whether it's diesel sludge or something else.

Lead ballast when not cast in place is sometimes added as shot. Heard of tar/pitch covering the lead but I expect other sealants have been used.
It is possible for petrol to degrade substances that are unaffected by diesel.

Do you have any ideas about what else could have blocked your filters so thoroughly if you don't think it was the brown stuff? Given that you said it was fresh diesel?

I 'do' think it was the brown stuff though. There was evidence of it in the filter bowl. Though, the filters themselves were black. Someone else suggested oil is leaking into the fuel, but I now can't see how it's oil. Can't see how the oil and fuel would mix. Though I was using oil on the trip. I used about a ltr in 500 miles.

I'm not sure why your commenting about lead shot why would ballast be in my fuel tank and there isn't any lead shot int anyway. I emptied the tank in December.

Before I ever use this tank again, I'll be ensuring all of this solidified brown stuff is gone. And I'll be wanting the walls back to raw metal.